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      https://www.ias.ac.in/article/fulltext/joaa/042/0086

    • Keywords

       

      Galaxies: star formation; galaxies: formation; galaxies: evolution; galaxies: IC3418; ultraviolet: galaxies.

    • Abstract

       

      We present the far ultraviolet (FUV) imaging of the nearest Jellyfish or Fireball galaxy IC3418/VCC 1217, in the Virgo cluster of galaxies, using Ultraviolet Imaging Telescope (UVIT) onboard the AstroSat satellite. The young star formation observed here in the 17 kpc long turbulent wake of IC3418,due to ram pressure stripping of cold gas surrounded by hot intra-cluster medium, is a unique laboratory that is unavailable in the Milky Way. We have tried to resolve star forming clumps, seen compact to GALEX UV images, using better resolution available with the UVIT and incorporated UV-optical imagesfrom Hubble Space Telescope archive. For the first time, we resolve the compact star forming clumps (fireballs) into sub-clumps and subsequently into a possibly dozen isolated stars. We speculate that many of them could be blue supergiant stars which are cousins of SDSS J122952.66$+$112227.8, the farthest star($\sim$17 Mpc) we had found earlier surrounding one of these compact clumps. We found evidence of star formation rate ($4–7.4 \times 10^{–4} \ M_{\odot}$ yr$^{–1}$) in these fireballs, estimated from UVIT flux densities, to beincreasing with the distance from the parent galaxy. We propose a new dynamical model in which the stripped gas may be developing vortex street where the vortices grow to compact star forming clumps due to self-gravity. Gravity winning over turbulent force with time or length along the trail can explain thepuzzling trend of higher star formation rate and bluer/younger stars observed in fireballs farther away from the parent galaxy.

    • Author Affiliations

       

      ANANDA HOTA1 ASHISH DEVARAJ2 ANANTA C PRADHAN3 C. S. STALIN2 KOSHY GEORGE4 ABHISEK MOHAPATRA3 SOO-CHANG REY5 YOUICHI OHYAMA6 SRAVANI VADDI7 RENUKA PECHETTI8 RAMYA SETHURAM2 JESSY JOSE9 JAYASHREE ROY10 CHIRANJIB KONAR11

      1. #eAstroLab, UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai 400 098, India.
      2. Indian Institute of Astrophysics, Koramangala II Block, Bangalore 560 034, India.
      3. Department of Physics and Astronomy, National Institute of Technology, Rourkela 769 008, India.
      4. Faculty of Physics, Ludwig-Maximilians-Universita¨t, Scheinerstr 1, 81679 Munich, Germany.
      5. Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134, Republic of Korea.
      6. Institute of Astronomy and Astrophysics, Academia Sinica, No. 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan.
      7. Arecibo Observatory, NAIC, HC3 Box 53995, Arecibo, PR 00612, USA.
      8. Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK.
      9. Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517 507, India.
      10. Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune 411 007, India.
      11. Amity Institute of Applied Sciences, Amity University Uttar Pradesh, Sector-125, Noida 201 303, India.
    • Dates

       
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